1. Field of the Invention
The present invention relates to a manufacturing method of a display device which can prevent the lowering of a yield rate of a display device having a semiconductor film. The present invention relates more particularly to a manufacturing method of a display device which can prevent the lowering of a yield caused by a defect attributed to the aggregation which is generated in the pseudo single crystallization of a silicon film by a continuous oscillation laser.
2. Description of the Related Art
In a so-called flat-panel-type display device such as a liquid crystal display panel or an organic EL panel, to build in a larger number of peripheral circuits including drive circuits on a substrate which constitutes the panel in addition to pixel circuits of a display region, the development of a high-performance low-temperature poly-silicon thin film transistor (poly-SiTFT (LTPS-TFT)) has been under way. The manufacture of the high-performance low-temperature poly-silicon thin film transistor requires the improvement of the crystallinity of a silicon film, and there has been studied a technique which can make a particle size of the silicon film large (pseudo single crystallization) compared to the crystallization performed using conventional excimer laser annealing (ELA).
As one of techniques for improving the crystallinity, there has been known a method which selectively grows crystals in the specific direction by radiating solid laser beams of continuous oscillation to a silicon film which is formed on a substrate surface by a CVD or the like (hereinafter referred to as SELAX) The selective pseudo single crystallization method referred to as SELAX is disclosed in JP-A-2002-222959 (patent document 1) and JP-A-2003-124136 (patent document 2).